The transportation exhibit at the Smithsonian's American History museum is one of my favorites. It's as much about the evolution of transportation technology as it is about the history of suburban sprawl. It's a pretty balanced approach to the issue too.

For automobiles to become a permanent fixture on the American landscape - rather than simply a toy for the rich - people needed to be convinced that they were reliable, useful, appropriate, and even necessary. In the early years of motoring, not all Americans were convinced that the new "devil wagons" were here to stay. But as people came to value the convenience of the car, and as they adapted it to their own needs, cars became a significant part of everyday life.

This statement is enlightening because today we take for granted that cars rule the urban landscape, and in fact, the "necessity" of them was not immediately obvious when they first came onto the market. In fact, the necessity of them was questioned pretty aggressively.

Today, people believe that cars are absolutely a necessity - and they're not entirely wrong. But it's because we made policy decisions throughout history that made it that way. The reason why sprawl happened the way it did is complex. It's not simply because people wanted it to happen, as some believe; nor is it simply because government pushed it to happen, as others believe. The reason is somewhere in the middle, but it didn't happen by accident.